In recent years, advances in technology, as well as ever evolving tastes in style, have led to substantial changes in the design of automobiles. One of the changes involves the power usage and complexity of the various electrical systems within automobiles, particularly alternative fuel vehicles, such as hybrid and electric vehicles.
Electric or hybrid vehicles often utilize electric motors as an alternative to internal combustion engines or other fuel-based engines. These electric motors generally operate on electricity from an energy storage device within the vehicle (e.g., a battery pack or an ultracapacitor). Rechargeable or plug-in vehicles allow these energy storage devices to be charged from an external power source when the vehicle is not in operation. For example, a vehicle may be plugged into or otherwise connected to a residential wall outlet to provide power from the main power supply for the residence to a charging circuit within the vehicle.
Often, a charging cord is used to connect the vehicle to an external power supply. These charging cords generally include a safety device or interrupt device, such as a charge current interrupt device (CCID), which disconnects the charging circuit whenever the device detects a current imbalance (or current leakage) between the conductors in the cord that exceeds a trip point. The trip point or level of imbalance is generally set at a high-enough level that avoids undesirable or nuisance trips as a result of exposure to environmental conditions (e.g., the cord is outside in the rain) during otherwise normal operating conditions (e.g., fault-free), yet low-enough that it provides adequate protection against fault conditions.
However, most residential power systems are equipped with a ground fault current interrupter (GFCI) or other residual current device designed with a significantly lower trip point than the safety device on the vehicle charging cord. In this situation, the device with the lower trip setting (i.e., the GFCI) will always trip before the safety device on the vehicle charging cord. This defeats the purpose of the safety device on the charging cord, and may result in undesirable nuisance trips during routine operations. Often, when the GFCI device trips, the user must manually reset the device which may result in an incomplete vehicle battery charge. In some cases, the GFCI device may be difficult to locate or access, placing additional burdens on the user.